It is worth a try at this point to clarify some misunderstandings about optimizers.
- Oracle8i and Oracle9i systems do not use the rule-based optimizer
Absolutely not true. Some publishers gave that information some time ago, but Oracle provides, it certainly is not.
- Guidelines can not be used in the case of rule-based optimizer
Most of the tips can be successfully used in SQL statements using rule-based optimizer.
- SQL command will be adjusted according to the rules made by the cost efficient
With a large bit of luck could happen, but the cost-based optimizer going to have to be prepared for the need to optimize the number of SQL commands. The author is not met, however, a system in which it would be impossible to change after such adjustment.
- Tuned SQL command will be run at cost efficiently according to the rules
This is unlikely, unless it has been written taking into account the characteristics of rule-based optimizer.
- You can not simultaneously use the rule-based optimizer and a cost
You can use both optimizers, if init.ora parameter file OPTIMIZER_MODE give the value CHOOSE, and some tables in the system is analyzed, and some do not. Be careful not to connect the tables, which were analyzed with tables that have not been analyzed.
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